New NIDA Research Reveals the Power of Social Reinforcement

When it is available and can be delivered appropriately and effectively, medication is a crucial part of treating addiction—but by itself, a pill or an injection may not be sufficient. Social support has long been known to be an important factor in a variety of recovery programs and treatment approaches. Now, for the first time, an animal study conducted by members of NIDA’s Intramural Research Program and a scientist in Italy illustrates just how potent social reinforcement can be, even in animals that are already “addicted” to drugs as reinforcing as heroin and methamphetamine.

The new study led by NIDA’s Dr. Marco Venniro required rats to choose between social interaction with another rat or access to heroin or methamphetamine. The animals consistently chose social interaction when given the choice, and this was true when they were first given access to the drug or when they were experienced drug takers.

To assess the level of addiction in their rats, the experimenters used a sophisticated set of behavioral paradigms that attempt to model the kinds of choices made by humans who are addicted to drugs. They include assessing how hard a rat will work for access to the drug and whether responding persists despite punishment (i.e., brief electric shocks). Individual differences emerge in these paradigms; but regardless, the social reinforcer always won out over the drug. Even when the rats were housed with other rats and thus lived in a social environment, they consistently chose further social contact over the option to self-administer the drug.

The experimenters manipulated the social reward by introducing delay and an aversive stimulus in some conditions. Addicted rats were only likely to choose the drug over social interaction (i.e., relapse) when access to other rats was sufficiently delayed or punished. It is a striking set of findings. Even though previous research had established that isolation led animals to self-administer drugs and that social housing was protective against drug use, no studies had given animals the ability to choose one or the other—conditions had always been controlled by the experimenter. (Some studies had used palatable food as a choice alternative, but not social contact.)

Another surprise concerned the phenomenon known as incubation of drug craving. Rats that regularly self-administer a drug display an increase in drug seeking following a period of abstinence (usually forced), similar to what many human drugs users experience following withdrawal—and often what prompts relapse. However, rats that became voluntarily abstinent by repeatedly choosing social interaction did not demonstrate this incubation effect.

The authors of this study point out that our social needs as humans are far more complex than the social needs of rats. In addition to social interactions and companionship (more immediate forms of social gratification), we also need more distal social expectations like the promise of meaningful participation in our community or society. But the findings of the study provide valuable insight into how recovery programs centered on mutual aid, as well as treatment approaches that emphasize social reinforcement, might help individuals overcome drug problems.

For example, one of the best-supported behavioral treatments is the community reinforcement approach (CRA), which centers on building a new social support system and increasing the value of other, non-drug rewards in the individual’s life. Other approaches like cognitive behavior therapy also seek to increase the salience of less immediate social rewards when patients are faced with the immediate temptations of drug use. Even recovery groups for people with drug or alcohol addictions based on 12-step or similar models depend in large part on building a new social structure in which the person can function. The new study’s authors argue that their findings lend weight to the argument that these kinds of behavioral approaches that incorporate complex social influences should be more widely studied and utilized.